nixos/modules/system/boot/loader/generic-extlinux-compatible/extlinux-conf-builder.sh

   1 #! @bash@/bin/sh -e
   2
   3 shopt -s nullglob
   4
   5 export PATH=/empty
   6 for i in @path@; do PATH=$PATH:$i/bin; done
   7
   8 usage() {
   9     echo "usage: $0 -t <timeout> -c <path-to-default-configuration> [-d <boot-dir>] [-g <num-generations>] [-n <dtbName>] [-r]" >&2
  10     exit 1
  11 }
  12
  13 timeout=                # Timeout in centiseconds
  14 menu=1                  # Enable menu by default
  15 default=                # Default configuration
  16 target=/boot            # Target directory
  17 numGenerations=0        # Number of other generations to include in the menu
  18
  19 while getopts "t:c:d:g:n:r" opt; do
  20     case "$opt" in
  21         t) # U-Boot interprets '0' as infinite
  22             if [ "$OPTARG" -lt 0 ]; then
  23                 # When negative (or null coerced to -1), disable timeout which means that we wait forever for input
  24                 timeout=0
  25             elif [ "$OPTARG" = 0 ]; then
  26                 # When zero, which means disabled in Nix module, disable menu which results in instant boot of the default item
  27                 # .. timeout is actually ignored by u-Boot but set here for the rest of the script
  28                 timeout=1
  29                 menu=0
  30             else
  31                 # Positive results in centi-seconds of timeout, which when passed with no input results in boot of the default item
  32                 timeout=$((OPTARG * 10))
  33             fi
  34             ;;
  35         c) default="$OPTARG" ;;
  36         d) target="$OPTARG" ;;
  37         g) numGenerations="$OPTARG" ;;
  38         n) dtbName="$OPTARG" ;;
  39         r) noDeviceTree=1 ;;
  40         \?) usage ;;
  41     esac
  42 done
  43
  44 [ "$timeout" = "" -o "$default" = "" ] && usage
  45
  46 mkdir -p $target/nixos
  47 mkdir -p $target/extlinux
  48
  49 # Convert a path to a file in the Nix store such as
  50 # /nix/store/<hash>-<name>/file to <hash>-<name>-<file>.
  51 cleanName() {
  52     local path="$1"
  53     echo "$path" | sed 's|^/nix/store/||' | sed 's|/|-|g'
  54 }
  55
  56 # Copy a file from the Nix store to $target/nixos.
  57 declare -A filesCopied
  58
  59 copyToKernelsDir() {
  60     local src=$(readlink -f "$1")
  61     local dst="$target/nixos/$(cleanName $src)"
  62     # Don't copy the file if $dst already exists.  This means that we
  63     # have to create $dst atomically to prevent partially copied
  64     # kernels or initrd if this script is ever interrupted.
  65     if ! test -e $dst; then
  66         local dstTmp=$dst.tmp.$$
  67         cp -r $src $dstTmp
  68         mv $dstTmp $dst
  69     fi
  70     filesCopied[$dst]=1
  71     result=$dst
  72 }
  73
  74 # Copy its kernel, initrd and dtbs to $target/nixos, and echo out an
  75 # extlinux menu entry
  76 addEntry() {
  77     local path=$(readlink -f "$1")
  78     local tag="$2" # Generation number or 'default'
  79
  80     if ! test -e $path/kernel -a -e $path/initrd; then
  81         return
  82     fi
  83
  84     copyToKernelsDir "$path/kernel"; kernel=$result
  85     copyToKernelsDir "$path/initrd"; initrd=$result
  86     dtbDir=$(readlink -m "$path/dtbs")
  87     if [ -e "$dtbDir" ]; then
  88         copyToKernelsDir "$dtbDir"; dtbs=$result
  89     fi
  90
  91     timestampEpoch=$(stat -L -c '%Z' $path)
  92
  93     timestamp=$(date "+%Y-%m-%d %H:%M" -d @$timestampEpoch)
  94     nixosLabel="$(cat $path/nixos-version)"
  95     extraParams="$(cat $path/kernel-params)"
  96
  97     echo
  98     echo "LABEL nixos-$tag"
  99     if [ "$tag" = "default" ]; then
 100         echo "  MENU LABEL NixOS - Default"
 101     else
 102         echo "  MENU LABEL NixOS - Configuration $tag ($timestamp - $nixosLabel)"
 103     fi
 104     echo "  LINUX ../nixos/$(basename $kernel)"
 105     echo "  INITRD ../nixos/$(basename $initrd)"
 106     echo "  APPEND init=$path/init $extraParams"
 107
 108     if [ -n "$noDeviceTree" ]; then
 109         return
 110     fi
 111
 112     if [ -d "$dtbDir" ]; then
 113         # if a dtbName was specified explicitly, use that, else use FDTDIR
 114         if [ -n "$dtbName" ]; then
 115             echo "  FDT ../nixos/$(basename $dtbs)/${dtbName}"
 116         else
 117             echo "  FDTDIR ../nixos/$(basename $dtbs)"
 118         fi
 119     else
 120         if [ -n "$dtbName" ]; then
 121             echo "Explicitly requested dtbName $dtbName, but there's no FDTDIR - bailing out." >&2
 122             exit 1
 123         fi
 124     fi
 125 }
 126
 127 tmpFile="$target/extlinux/extlinux.conf.tmp.$$"
 128
 129 cat > $tmpFile <<EOF
 130 # Generated file, all changes will be lost on nixos-rebuild!
 131
 132 # Change this to e.g. nixos-42 to temporarily boot to an older configuration.
 133 DEFAULT nixos-default
 134
 135 TIMEOUT $timeout
 136 EOF
 137
 138 [ "$menu" == "1" ] \
 139   && echo "MENU TITLE ------------------------------------------------------------" >> $tmpFile
 140
 141 addEntry $default default >> $tmpFile
 142
 143 if [ "$numGenerations" -gt 0 ]; then
 144     # Add up to $numGenerations generations of the system profile to the menu,
 145     # in reverse (most recent to least recent) order.
 146     for generation in $(
 147             (cd /nix/var/nix/profiles && ls -d system-*-link) \
 148             | sed 's/system-\([0-9]\+\)-link/\1/' \
 149             | sort -n -r \
 150             | head -n $numGenerations); do
 151         link=/nix/var/nix/profiles/system-$generation-link
 152         addEntry $link "${generation}-default"
 153         for specialisation in $(
 154             ls /nix/var/nix/profiles/system-$generation-link/specialisation \
 155             | sort -n -r); do
 156             link=/nix/var/nix/profiles/system-$generation-link/specialisation/$specialisation
 157             addEntry $link "${generation}-${specialisation}"
 158         done
 159     done >> $tmpFile
 160 fi
 161
 162 mv -f $tmpFile $target/extlinux/extlinux.conf
 163
 164 # Remove obsolete files from $target/nixos.
 165 for fn in $target/nixos/*; do
 166     if ! test "${filesCopied[$fn]}" = 1; then
 167         echo "Removing no longer needed boot file: $fn"
 168         chmod +w -- "$fn"
 169         rm -rf -- "$fn"
 170     fi
 171 done